WO 9824014 describes a system of testing fuel injection valves by means of pressurized gas. Such a system is not sufficient for testing of gas shut-down valves for combustion engines where even the smallest leakages are unacceptable and may result in an explosion.
A system of testing of gas injection valves is also known. This system is however not satisfactory.
Finally GB 1285705 describes an apparatus for testing a valve. The valve is placed in a holder and the valve is in closed condition influenced by a not burnable pressurized gas to check whether the valve seat is closed. However this apparatus is not designed for testing of a valve which is surrounded by a sealing ring when it is in operation.